The present disclosure generally relates to semiconductor devices, and particularly to complementary metal-oxide-semiconductor (CMOS) field effect transistors including an oxygen scavenging spacer, and methods of manufacturing the same.
Oxygen diffusion into a “high-k gate dielectric,” i.e., a gate dielectric including a dielectric metal oxide having a dielectric constant greater than 8.0, and accompanying additional oxidation of the high-k gate dielectric cause a shift in the dielectric constant of the high-k gate dielectric. Such a shift in the dielectric constant of the high-k gate dielectric induces changes in the threshold voltage of a complementary metal oxide semiconductor (CMOS) transistor employing the high-k gate dielectric. Thus, it is necessary to prevent diffusion of oxygen into a high-k gate dielectric of the CMOS transistor in order to provide a stable threshold voltage that does not change with use of the CMOS transistor or in time.